The present invention relates to a process for preparing dry extracts.
Extracts from plants or plant parts are widely employed in the food and drug fields. In many cases, it is appropriate to dry the thus obtained extracts in order the volume of the extracts. As far as other auxiliary agents are needed for the further processing of the dry extract, these are usually admixed with the liquid extract, followed by commonly drying them. Depending on what use is intended for the thus obtained dry products, further processing steps, such as wet granulation, fluidized-bed drying, compaction etc., can follow.
It has been the object of the present invention to provide a particularly simple process for adding further substances to an extract to be dried.
According to the invention, this object is achieved by a process for preparing dry extracts from a liquid extract and at least one additional substance by a spray-drying process, wherein said at least one additional substance is added to the spray-drying process in a dry form during the spray-drying process.
The wet extract droplets formed by the spraying will mix with said at least one additional substance and are dried on their common way through the spray-dryer, The residual moisture is generally below 5%.
Surprisingly, in this way, a homogeneous free-flowing powder can be obtained, which can be used, for example, directly for tabletting. Such a product is superior to both one obtained by commonly drying a solution of the extract and auxiliary agent, and one obtained by adding the auxiliary agent to the dried extract, with respect to galenic properties, especially tabletting property. Thus, the proportion of auxiliary agent can be significantly reduced as compared to conventional processes, so that smaller tablets can be produced with the same load of active substance, or more active substance can be introduced in predetermined tablet sizes.
The process is particularly useful if the liquid extract is the extract of a medicinal plant whose extract is to be administered in the form of tablets.
Said at least one additional substance will then be a galenic auxiliary agent. Galenic auxiliary agents are known to the skilled person. There may be mentioned, for example, lactose, maltodextrin, dextrin, dry glucose, starch, microcrystalline cellulose, silicated microcrystalline cellulose, Povidone(copyright), polyethylene glycol, calcium phosphate, magnesium stearate, precipitated silicic acid, precipitated silica, highly dispersed silica, sorbitol, mannitol, or mixtures thereof.
The particle size of the additional substance employed is of less importance. Suitable particle sizes are within a range of from 1 to 500 xcexcm.
The process according to the invention results in adhesion of the auxiliary agents to the extracts. Therefore, the invention also relates to the dry extract thus obtained, and to a medicament containing the dry extract according to the invention.
Preferably, the medicament according to the invention is a medicament in a tablet form.
For performing the process, a usual spray-drying plant can be used in which the liquid extract is introduced into a spray tower and drying air is simultaneously fed. By spraying into a hot-air current, the liquid products are quickly and mildly dried within seconds or fractions of seconds. The liquid extract to be dried typically contains from 5 to 70% of dry substance and is introduced into the spray tower at a pressure within a range of from 10 to 150 bar through one or more high-pressure nozzles. Usually, the temperature of the fed-in drying air is between 120 and 350xc2x0 C., In the process according to the invention, the dry additional substance or a mixture of such substances is also introduced into the spray tower using blow conveyance, preferably in the vicinity of the spraying nozzles for the liquid extract.
For example, the design could be as follows:
A liquid extract is provided in a storage vessel. On a second position, there are dosing scales with the additional substance employed according to the invention in a dry form. The liquid extract is sprayed in together with the finely powdered additional substance at the top of the spray tower through high-pressure nozzles using a pump. Hot air is introduced into the spray tower from below. The exhaust air leaves at the top end of the spray tower and is optionally conducted to a heat exchanger. The dried product is conducted onto a vibrating bed at the lower end of the spray tower and introduced into the further production process. Alternatively, the product may be fed into a cyclone.